Musar su Numeri 24:20

It is well known that Amaleik, who is the “first of nations” (Bamidbar 24:20), is a descendant of the wicked Eisav. He has a share in the concept of an “other god,” because the value of Amaleik [עמלק] is 240, which is equal to the words אל אחר — “other god.” The corresponding principle on the side of holiness is רוח יהו"ה — “the spirit of Hashem” (Shoftim 11:29), which also has a value of 240. Corresponding to the husks of the ox and donkey on the side of holiness are the two Moshiachs. Moshiach son of David overcomes the husk of the donkey, as it is stated, “A humble man riding on a donkey” (Zecharyah 9:9), while Moshiach son of Yosef is called an “ox,” as in the verse, “He has the majesty of a firstborn ox” (Devarim 33:17). It is related in the Zohar (3:124b; Zohar Chadash Ruth, 101b) that from the joining of the two husks of the ox and donkey came another husk known as the “viper” [tzefa], as in the verse, “From the root of the serpent comes a viper” (Yeshayahu 14:29). The value of צפע equals that of “Amaleik” — 240. Therefore the ink with which a Torah scroll is written must contain mei afatz — “gallnut water” (Gittin 19a), because the word עפץ is the reverse of צפע. Thus, by writing the Torah scroll with gallnut water, we subjugate the husk of the viper.